Actinic ray curable composition, actinic ray curable ink, image forming method, and ink jet recording apparatus

ABSTRACT

Disclosed are an actinic ray curable composition, an actinic ray curable ink, an image recording method, and an ink jet recording apparatus, the actinic ray curable composition containing a photo acid generator, and an oxetane compound I represented by the following formula 1,  
                 
 
     wherein R 1 , R 2 , R 3 , R 4 , R 5 , and R 6  independently represent a hydrogen atom, a fluorine atom, an alkyl group having from 1 to 6 carbon atoms, a fluoroalkyl group having from 1 to 6 carbon atoms, an allyl group, an aryl group, a furyl group or a thienyl group, and wherein the longer C—O bond distance of the two C—O bond distances in formula 1 is from 0.1464 to 0.1500 nm.

FIELD OF THE INVENTION

[0001] The present invention relates to an actinic ray curablecomposition, an actinic ray curable ink, an image recording method, andan ink jet recording apparatus, which stably form an image with highresolution and excellent character quality, and exhibit no colorcontamination on various kinds of recording materials under variouscircumstances.

BACKGROUND OF THE INVENTION

[0002] In recent years, an ink jet recording method has found wideapplication in various kinds of graphic art fields such as photography,various kinds of printing, marking and specific printing such as a colorfilter because of being able to form images easily and inexpensively.Particularly, it has also become possible to obtain image qualitycomparable to silver salt photograph images by utilizing a recordingapparatus which ejects and controls fine dots, ink in which a colorreproduction range, durability and ejection suitability have beenimproved, and exclusive paper in which ink absorption, color formingproperty of colorants and surface gloss have been greatly improved.Image quality improvement of an ink jet recording method of today hasbeen achieved only when a complete set of a recording apparatus, ink andexclusive paper is prepared.

[0003] However, an ink jet system which requires exclusive paper isproblematic in respect to limitation of a recording medium and cost upof a recording medium. Therefore, many attempts have been made whichrecord on a recording medium different from exclusive paper, employingan ink jet recording. Concretely, there are methods such as aphase-conversion ink jet method utilizing wax which is solid at roomtemperature, a solvent-type ink jet method utilizing an ink which ismainly comprised of a rapid-drying organic solvent and a UV ink jetmethod in which an ink is cross-linked by ultraviolet (UV) light afterrecording.

[0004] Among them, a UV ink jet method has been noted recently inrespect to odor relatively lower than that of a solvent-type ink jetmethod, rapid drying property and capability of recording on a recordingmedium having no ink absorption. UV-curable ink jet inks are disclosed,for example, in Japanese Patent Publication No. 5-54667, JP-A(hereinafter, JP-A refers to Japanese Patent Publication Open to PublicInspection) No. 6-20204 and Japanese Translated PCT Patent PublicationNo. 2000-504778.

[0005] However, even when these inks are employed, the dot diameter ofink ejected onto recording material changes significantly depending onthe kind of recording material or operating conditions, and it istherefore impossible to form an image with high resolution on variousrecording materials.

[0006] As UV-curable inks, there are a radical polymerization typeUV-curable ink, which is comprised mainly of an acryl composition, and acation polymerization type UV-curable ink.

[0007] The radical polymerization type UV-curable ink has problems inthat the polymerization reaction is inhibited by oxygen on account ofits polymerization mechanism, resulting in lowering of curability. Incontrast, the cation polymerization type UV-curable ink is notinfluenced by oxygen, however, it has problem in that the polymerizationreaction is susceptible to moisture in the molecular level on account ofits polymerization mechanism.

SUMMARY OF THE INVENTION

[0008] The present invention has been made in view of the above. Anobject of the invention is to provide an actinic ray curable compositionand an actinic ray curable ink, which provide an image with highresolution and excellent character quality, without causing colorcontamination under various recording circumstances, and an imagerecording method and an ink jet recording apparatus each employing theactinic ray curable ink.

BRIEF DESCRIPTION OF THE DRAWING

[0009]FIG. 1 is a front view illustrating a main constitution of arecording apparatus of the invention.

DESCRIPTION OF THE INVENTION

[0010] The above object has been achieved by the followingconstitutions.

[0011] 1. An actinic ray curable composition containing a photo acidgenerator, and an oxetane compound I represented by the followingformula 1,

[0012] wherein R₁, R₂, R₃, R₄, R₅, and R₆ independently represent ahydrogen atom, a fluorine atom, an alkyl group having from 1 to 6 carbonatoms, a fluoroalkyl group having from 1 to 6 carbon atoms, an allylgroup, an aryl group, a furyl group or a thienyl group, and wherein thelonger C—O bond distance of the two C—O bond distances in formula 1 isfrom 0.1464 to 0.1500 nm.

[0013] 2. The actinic ray curable composition of item 1 above, whereinR₃, R₄, R₅ and R₆ in formula 1 atom are not simultaneously hydrogenatoms.

[0014] 3. The actinic ray curable composition of item 1 above, whereinthe composition further contains an oxetane compound II having oneoxetane ring which falls outside formula 1 or an oxetane compound IIIhaving two or more oxetane rings.

[0015] 4. The actinic ray curable composition of item 1 above, whereinthe composition further contains an oxirane compound having an oxiranering.

[0016] 5. The actinic ray curable composition of item 1 above, whereinthe composition has a viscosity at 25 ° C. of from 7 to 50 mPa.s.

[0017] 6. An actinic ray curable composition containing a photo acidgenerator, and an oxetane compound I′ represented by the followingformula 1,

[0018] wherein R₁, R₂, R₃, R₄, R₅, and R₆ independently represent ahydrogen atom, a fluorine atom, an alkyl group having from 1 to 6 carbonatoms, a fluoroalkyl group having from 1 to 6 carbon atoms, an allylgroup, an aryl group, a furyl group or a thienyl group, and wherein informula 1, the longer C—O bond distance of the two C—O bond distances isfrom 0.1435 to 0.1461 nm, and the oxygen atom has a charge of from−0.330 to −0.281.

[0019] 7. The actinic ray curable composition of item 6 above, whereinR₃, R₄, R₅ and R₆ in formula 1 atom are not simultaneously hydrogenatoms.

[0020] 8. The actinic ray curable composition of item 6 above, whereinthe composition further contains an oxetane compound II having oneoxetane ring which falls outside formula 1 or an oxetane compound IIIhaving two or more oxetane rings.

[0021] 9. The actinic ray curable composition of item 6 above, whereinthe composition further contains an oxirane compound having an oxiranering.

[0022] 10. The actinic ray curable composition of item 6 above, whereinthe composition has a viscosity at 25° C. of from 7 to 50 mPa.s.

[0023] 11. An actinic ray curable ink, containing pigment, a photo acidgenerator, and an oxetane compound I represented by the followingformula 1,

[0024] wherein R₁, R₂, R₃, R₄, R₅, and R₆ independently represent ahydrogen atom, a fluorine atom, an alkyl group having from 1 to 6 carbonatoms, a fluoroalkyl group having from 1 to 6 carbon atoms, an allylgroup, an aryl group, a furyl group or a thienyl group, and wherein thelonger C—O bond distance of the two C—O bond distances in formula 1 isfrom 0.1464 to 0.1500 nm.

[0025] 12. An actinic ray curable ink, containing pigment, a photo acidgenerator, and an oxetane compound I′ represented by the followingformula 1,

[0026] wherein R₁, R₂, R₃, R₄, R₅, and R₆ independently represent ahydrogen atom, a fluorine atom, an alkyl group having from 1 to 6 carbonatoms, a fluoroalkyl group having from 1 to 6 carbon atoms, an allylgroup, an aryl group, a furyl group or a thienyl group, and wherein informula 1, the longer C—O bond distance of the two C—O bond distances isfrom 0.1435 to 0.1461 nm, and the oxygen atom has a charge of from—0.330 to —0.281.

[0027] 13. An image forming method comprising the steps of ejectingdroplets of the actinic ray curable ink of item 11 above through anozzle of an ink-jet recording head onto a recording material to depositthe ink on the recording material, and irradiating the ink on therecording material employing an actinic ray, 0.001 to 2.0 seconds afterthe ejected ink has been deposited on the recording material, wherebythe cured ink layer is formed.

[0028] 14. The image forming method of item 13 above, wherein thethickness of the cured ink layer is from 2 to 20 μm.

[0029] 15. The image forming method of item 13 above, wherein the volumeof the ink droplets to be ejected is from 2 to 15 pl.

[0030] 16. The image forming method of item 13 above, wherein theejecting of the actinic ray curable ink is carried out at 35 to 100° C.

[0031] 17. An image forming method comprising the steps of ejectingdroplets of the actinic ray curable ink of item 12 above through anozzle of an ink-jet recording head onto a recording material to depositthe ink on the recording material, and irradiating the ink on therecording material employing an actinic ray, 0.001 to 2.0 seconds afterthe ejected ink has been deposited on the recording material, wherebythe cured ink layer is formed.

[0032] 18. The image forming method of item 17 above, wherein thethickness of the cured ink layer is from 2 to 20 μm.

[0033] 19. The image forming method of item 17 above, wherein the volumeof the ink droplets to be ejected is from 2 to 15 pl.

[0034] 20. The image forming method of item 17 above, wherein theejecting of the actinic ray curable ink is carried out at 35 to 100° C.

[0035] 2-1. An actinic ray curable composition containing a photo acidgenerator, and an oxetane compound I represented by formula 1 abovehaving an oxetane ring, wherein R₁, R₂, R₃, R₄, R₅, and R₆ independentlyrepresent a hydrogen atom, a fluorine atom, an alkyl group having from 1to 6 carbon atoms, a fluoroalkyl group having from 1 to 6 carbon atoms,an allyl group, an aryl group, a furyl group or a thienyl group, andwherein the longer C—O bond distance of the two C—O bond distances informula 1 is from 0.1464 to 0.1500 nm.

[0036] 2-2. The actinic ray curable composition of item 2-1 above,wherein R₃, R₄, R₅ and R₆ in formula 1 atom are not simultaneouslyhydrogen atoms.

[0037] 2-3. The actinic ray curable composition of item 2-1 or 2-2above, wherein the composition contains a monofunctional oxetanecompound having one oxetane ring and a bifunctional oxetane compoundhaving two or more oxetane rings.

[0038] 2-4. The actinic ray curable composition of any one of items 2-1through 2-3 above, wherein the composition contains a compound having anoxirane ring.

[0039] 2-5. The actinic ray curable composition of any one of items 2-1through 2-4 above, wherein the composition has a viscosity at 25° C. offrom 7 to 50 mPa.s.

[0040] 2-6. An actinic ray curable ink comprising the composition of anyone of items 2-1 through 2-5 above, and pigment.

[0041] 2-7. An image forming method comprising the steps of ejecting theactinic ray curable ink of item 2-6 above through a nozzle of an ink-jetrecording head onto a recording material to deposit the ink on therecording material, and irradiating the ink on the recording materialemploying an actinic ray, 0.001 to 2.0 seconds after the ejected ink hasbeen deposited on the recording material, whereby the ink is cured toform an ink image.

[0042] 2-8. An image forming method comprising the steps of ejecting theactinic ray curable ink of item 2-6 above through a nozzle of an ink-jetrecording head onto a recording material to deposit the ink on therecording material, and irradiating the ink on the recording materialemploying an actinic ray to cure the ink to form a cured ink layer, thethickness of the cured ink layer being from 2 to 20μm.

[0043] 2-9. An image forming method comprising the steps of ejectingdroplets of the actinic ray curable ink of item 2-6 above through anozzle of an ink-jet recording head onto a recording material to depositthe ink on the recording material, wherein the volume of the droplets ofthe ink to be ejected is from 2 to 15 pl.

[0044] 2-10. An ink jet recording apparatus employing any one of theimage forming methods of items 2-7 through 2-9, wherein the apparatusejects the actinic ray curable ink at 35 to 100° C.

[0045] 3-1. An actinic ray curable composition containing a photo acidgenerator, and an oxetane compound I′ represented by formula 1 abovehaving an oxetane ring, wherein R₁, R₂, R₃, R₄, R₅, and R₆ independentlyrepresent a hydrogen atom, a fluorine atom, an alkyl group having from 1to 6 carbon atoms, a fluoroalkyl group having from 1 to 6 carbon atoms,an allyl group, an aryl group, a furyl group or a thienyl group, andwherein the longer C—O bond distance of the two C—O bond distances informula 1 is from 0.1435 to 0.1461 nm, and the oxygen atom of formula 1has a charge of from —0.330 to —0.281.

[0046] 3-2. The actinic ray curable composition of item 3-1 above,wherein R₃, R₄, R₅ and R₆ in formula 1 atom are not simultaneouslyhydrogen atoms.

[0047] 3-3. The actinic ray curable composition of item 3-1 or 3-2above, wherein the composition contains a monofunctional oxetanecompound having one oxetane ring and a bifunctional oxetane compoundhaving two or more oxetane rings.

[0048] 3-4. The actinic ray curable composition of any one of items 3-1through 3-3 above, wherein the composition contains a compound having anoxirane ring.

[0049] 3-5. The actinic ray curable composition of any one of items 3-1through 3-4 above, wherein the composition has a viscosity at 25° C. offrom 7 to 50 mPa.s.

[0050] 3-6. An actinic ray curable ink comprising the composition of anyone of items 3-1 through 3-5 above, and pigment.

[0051] 3-7. An image forming method comprising the steps of ejectingdroplets of the actinic ray curable ink of item 3-6 above through anozzle of an ink-jet recording head onto a recording material to depositthe ink on the recording material, and irradiating the ink on therecording material employing an actinic ray, 0.001 to 2.0 seconds afterthe ejected ink has been deposited on the recording material, wherebythe ink is cured to form an ink image.

[0052] 3-8. An image forming method comprising the steps of ejectingdroplets of the actinic ray curable ink of item 3-6 above through anozzle of an ink-jet recording head onto a recording material to depositthe ink on the recording material, and irradiating the ink on therecording material employing an actinic ray to cure the ink to form acured ink layer, the thickness of the cured ink layer being from 2 to 20μm.

[0053] 3-9. An image forming method comprising the steps of ejectingdroplets of the actinic ray curable ink of item 3-6 above through anozzle of an ink-jet recording head onto a recording material to depositthe ink on the recording material, wherein the volume of the droplets ofthe ink to be ejected is from 2 to 15 pl.

[0054] 3-10. An ink jet recording apparatus employing any one of theimage forming methods of items 3-7 through 3-9, wherein the apparatusejects the actinic ray curable ink at 35 to 100° C.

[0055] It has been found that the use in the actinic ray curablecomposition of the oxetane compound I or I′ represented by formula 1containing an oxetane ring markedly improves curability of thecomposition and provides excellent curability regardless of curingconditions (temperature or humidity) under which the composition iscured. The oxetane compound represented by formula 1 is preferably anoxetane compound in which R₃, R₄, R₅, and R₆ in formula 1 are notsimultaneously hydrogen atoms.

[0056] In Japanese Patent O.P.I. Publication No. 2001-181386 isdisclosed a curable composition containing an oxetane compound. Theoxetane compound disclosed therein is one in which the C—O bond distancedefined in the invention falls outside the scope of the invention, andthe curable composition provides insufficient curability, in whichcurability greatly varies due to curing conditions such as temperatureor humidity condition, which cannot be put into practical use. InJapanese Patent O.P.I. Publication Nos. 2000-256571 and 2000-63371 aredisclosed curable compositions containing an oxetane compound. However,these compositions are heat curable compositions, which objects arequite different from those of the invention.

[0057] The actinic ray curable ink of the invention, comprising theactinic ray curable composition of the invention and pigment, when it isemployed as ink for an ink jet recording, is excellent in ink ejectingstability, which is the most important problem in ink jet recording.Further, the actinic ray curable ink of the invention makes it possibleto easily control the dot diameter of the ink ejected onto recordingmaterial without being influenced by recording circumstances, and toform an image with good reproduction and high image quality. This ink isepoch-making.

[0058] Next, the present invention will be explained in detail.

[0059] First, the oxetane compound I or I′ represented by formula 1having an oxetane ring will be explained.

[0060] In formula 1, R₁, R₂, R₃, R₄, R₅, and R₆ independently representa hydrogen atom or a substituent. It is preferred that R₃, R₄, R₅, andR₆ are not simultaneously hydrogen atoms.

[0061] In formula 1, examples of the substituent represented by R₁, R₂,R₃, R₄, R₅, and R₆ include a fluorine atom, an alkyl group having from 1to 6 carbon atoms (for example, a methyl group, an ethyl group, a propylgroup, a butyl group, etc.), a fluoroalkyl group having from 1 to 6carbon atoms, an allyl group, an aryl group (for example, a phenylgroup, a naphthyl group, etc.), a furyl group and a thienyl group. Thesegroups described above are substituted or unsubstituted.

[0062] In the invention, the C—O bond distance in formula 1 is from0.1464 to 0.1500 nm, wherein the bond distance in formula 1 (hereinafteralso referred to as the C—O bond distance in the invention) representsthe longer C—O bond distance of the two C—O bond distances in formula 1,or in formula 1, the C—O bond distance in the invention is from 0.1435to 0.1461 nm and the charge of the oxygen atom is from —0.330 to —0.281.

[0063] The “charge” of the oxygen atom and “bond distance” hereinreferred to imply values obtained by molecular orbital calculationemploying WinMOPAC (produced by FUJITU Co., Ltd.).

[0064] The content of the oxetane compound I or I′ in the actinic raycurable composition is preferably from 5 to 90% by weight, and morepreferably from 10 to 80% by weight, based on the total weight of thecomposition.

[0065] Examples of an oxetane compound II having one oxetane ring in themolecule, which falls outside formula 1, include oxetane compoundsrepresented by the following formulae 2, 3, 4, and 5.

[0066] In formulae 2, 3, 4 and 5 above, R₁, R₂, R₃, R₄, R₅ and R₆independently represent a hydrogen atom or a substituent, and Zrepresents an oxygen atom, a sulfur atom, a divalent hydrocarbon groupor a divalent hydrocarbon group in which an oxygen atom or a sulfur atomis intervened.

[0067] In formulae 2, 3, 4 and 5 above, the substituent represented byR₁, R₂, R₃, R₄, R₅ and R₆ is the same as those denoted in R₁, R₂, R₃,R₄, R₅ and R₆ of formula 1.

[0068] In the formula 2 through 5, R₇ and R₈ independently represent analkyl group having from 1 to 6 carbon atoms (for example, a methylgroup, an ethyl group, a propyl group, a butyl group, etc.), an alkenylgroup having from 2 to 6 carbon atoms (a 1-propenyl group, a 2-propenylgroup, a 2-methyl-1-propenyl group, a 2-methyl-2-propenyl group, a1-butenyl group, a 2-butenyl group, a 3-butenyl group, etc.), an arylgroup (for example, a phenyl group, a naphthyl group, etc.), an aralkylgroup (for example, a benzyl group, a fluorobenzyl group, amethoxybenzyl group), an acyl group having from 1 to 6 carbon atoms (apropylcarbonyl group, a butylcarbonyl group, a pentylcarbonyl group,etc.), an alkoxycarbonyl group having from 1 to 6 carbon carbons (forexample, an ethoxycarbonyl group, a propoxycarbonyl group, abutoxycarbonyl group, etc.), an alkylcarbamoyl group having from 1 to 6carbon atoms (for example, a propylcarbamoyl group, abutylpentylcarbamoyl group, etc.), and an alkoxycarbamoyl group (forexample, an ethoxycarbamoyl group, etc.).

[0069] In formulae 2 through 5, the divalent hydrocarbon grouprepresented by Z is an alkylene group (for example, an ethylene group, atrimethylene group, a tetramethylene group, a propylene group, anethylethylene group, a pentamethylene group, a hexamethylene group, aheptamethylene group, an octamethylene group, a nonamethylene group, adecamethylene group, etc.), an alkenylene group (for example, a vinylenegroup, a propenylene group, etc.), an alkinylene group (an ethynylenegroup, or 3-pentynylene group, etc.). The divalent hydrocarbon grouprepresented by Z in which an oxygen atom or a sulfur atom is intervenedis the alkylene group, alkenylene group, or alkynyl group describedabove each having an oxygen atom or a sulfur atom intervened therein.

[0070] It is preferred in formulae 2 through 5 that R₁ is a lower alkylgroup, and particularly an ethyl group, R₇ and R₈ are independently apropyl group, a phenyl group or a benzyl group, and Z is the divalenthydrocarbon group, particularly, an alkylene group, an alkenylene group,or an alkynylene group. It is also preferred in formulae 2 through 5that R₃, R₄, R₅, and R₆ are not simultaneously hydrogen atoms.

[0071] Examples of an oxetane compound III having two or more oxetanerings in the molecule include compounds represented by the followingformulae 6 and 7.

[0072] In formulae 6 and 7 above, m is 2, 3, or 4, and Z is the same asthose denoted in Z of formulae 2 through 5.

[0073] R₁ through R₆ independently represent a hydrogen atom, a fluorineatom, an alkyl group having a carbon atom number of from 1 to 6 such asa methyl group, an ethyl group, a propyl group or a butyl group, afluoroalkyl group having a carbon atom number of from 1 to 6, an allylgroup, an aryl group, or a furyl group. In formula 6, it is preferredthat R₃, R₄, R₅, and R₆ are not simultaneously hydrogen atoms.

[0074] R₉ represents a straight chain or branched chain alkylene grouphaving from 1 to 12 carbon atoms, a straight chain or branched chainpoly(alkylene oxy) group, or a divalent group selected from the groupconsisting of the following formula 9, 10 and 11. The straight chain orbranched chain alkylene group having from 1 to 12 carbon atoms ispreferably a group represented by the following formula 8.

[0075] In formula 8, R₁₀ represents a lower alkyl group such as a methylgroup, an ethyl group, or propyl group.

[0076] In the formula 9, “n” represents an integer of from 0 to 2000.R₁₁ represents an alkyl group having from 1 to 10 carbon atoms (forexample, a methyl group, an ethyl group, a propyl group, a butyl group,a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonylgroup, etc.), or a group represented by the following formula 12. R₁₂represents an alkyl group having from 1 to 10 carbon atoms (for example,a methyl group, an ethyl group, a propyl group, a butyl group, a pentylgroup, a hexyl group, a heptyl group, an octyl group, a nonyl group,etc.).

[0077] In the formula 12, “j” represents an integer of from 0 to 100.R₁₃ represents an alkyl group having from 1 to 10 carbon atoms (forexample, a methyl group, an ethyl group, a propyl group, a butyl group,a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonylgroup, etc.).

[0078] In the formula 10, R₁₄ represents an alkyl group having from 1 to10 carbon atoms (for example, a methyl group, an ethyl group, a propylgroup, a butyl group, a pentyl group, a hexyl group, a heptyl group, anoctyl group, a nonyl group, etc.), an alkoxy group having from 1 to 10carbon atoms (for example, a methoxy group, an ethoxy group, a propoxygroup, a butoxy group, a pentoxy group, etc.), a halogen atom (forexample, a fluorine atom, a chlorine atom, a bromine atom, a iodineatom, etc.), a nitro group, a cyano group, a mercapto group, analkoxycarbonyl group (for example, a methyloxycarbonyl group, anethyloxycarbonyl group, a butyloxycarbonyl group, etc.), or a carboxylgroup.

[0079] In the formula 10, R₁₅ represents an oxygen atom, a sulfur atom,—NH—, —SO—, —SO₂—, —(CH₂)—, —C(CH₃)₂— or —(CF₃)₂—.

[0080] A preferred partial structure in the molecule of the oxetanecompound having an oxetane ring used in the invention will be explainedbelow.

[0081] In formula 6 or 7, R₁ is preferably a lower alkyl group such as amethyl group, an ethyl group, or a propyl group, and more preferably anethyl group. R₉ is preferably a hexamethylene group or one in which R₁₄in formula 10 above is a hydrogen atom.

[0082] In formula 8 above, R₁₀ is preferably an ethyl group, and informulae 9 and 12 above, R₁₂ and R₁₃ each are preferably hydrogen atoms.In formula 6 above, it is preferred that R₃ through R₆ are notsimultaneously hydrogen atoms.

[0083] Examples of an oxetane compound III having two or more oxetanerings in the molecule include an oxetane compound represented by thefollowing formulae 13.

[0084] In the formula 13, r is an integer of from 25 to 200, R₁₆represents an alkyl group having from 1 to 4 carbon atoms or atrialkylsilyl group. R₁ and R₄ through R₆ are the same as those denotedin formula 1. It is preferred that R₃ through R₆ are not simultaneouslyhydrogen atoms.

[0085] Exemplified compounds of the oxetane compound I represented byformula 1 wherein the longer C—O bond distance of the two C—O bonddistances in formula 1 is form 0.1464 to 0.1500 nm, will be shown inTable 1 below, but the invention is not specifically limited thereto.TABLE 1 Formula 1

*1 C—O Exemplified bond compound distance No. R₅ R₆ RCR₃ R₄ R₁ R₂ (nm) 1—CH₃ H H H —CH₃ —CH₃ 0.1464 2 —CH₂CH₃ H H H —CH₃ —CH₃ 0.1464 3—CH₂CH₂CH₃ H H H —CH₃ —CH₃ 0.1464 4 —CH(CH₃)CH₃ H H H —CH₃ —CH₃ 0.1464 5—(CH₂)₇CH₃ H H H —CH₃ —CH₃ 0.1464 6 *2 H H H —CH₃ —CH₃ 0.1464 7 —CH₃ CH3H H —CH₃ —CH₃ 0.1470 8 —CH₂CH₂CH₃ —CH₂CH₂CH₃ H H —CH₃ —CH₃ 0.1475 9 *2*2 H H —CH₃ —CH₃ 0.1474 10 *3 H —CFH₂ H —CH₃ —CH₃ 0.1464 11 *3 H —CF₂H H—CH₃ —CH₃ 0.1467 12 —CH₃ H —CF₂H H —CH₃ —CH₃ 0.1463 13 —CH₃ H —CF₃ H—CH₃ —CH₃ 0.1470 14 *4 H H H —CH₃ —CH₃ 0.1472 15 *5 H H H —CH₃ —CH₃0.1480 16 *6 H H H —CH₃ —CH₃ 0.1463 *1: The C—O bond distance representsthe longer C—O bond distance of the two C—O bond distances in formula 1.Exemplified compound 7-2: a bifunctional compound corresponding toExemplified compound 7

C—O bond distance: 0.1471 nm Exemplified compound 7-3: a bifunctionalcompound corresponding to Exemplified compound 7 (with an ether bond)

C—O bond distance: 0.1471 nm *2

*3

4

*5

*6

[0086] Exemplified compounds 1-2 through 6-2 and 8-2 through 16-2 arecited as bifunctional compounds, which correspond to Exemplifiedcompounds 1 through 6 and 8 through 16, respectively, in the same manneras in Exemplified compound 7-2, the bifunctional compound correspondingto Exemplified compound 7. Exemplified compounds 1-3 through 6-3 and 8-3through 16-3 are cited as bifunctional compounds (having an etherbound), which correspond to Exemplified compounds 1 through 6 and 8through 16 in the same manner as in Exemplified compound 7-3, thebifunctional compound (having an ehter bond) corresponding toExemplified compound 7.

[0087] Exemplified compounds of the oxetane compound I′ in the inventionrepresented by formula 1, in which in formula 1, the C—O bond distancein the invention is from 0.1435 to 0.1461 nm and the charge of theoxygen atom is form −0.330 to −0.281, will be shown in Table 2-1, butthe invention is not specifically limited thereto. TABLE 2-1 Formula 1

*1 C—O Charge Exemplified bond of compound distance oxygen No. R₅ R₆ R₃R₄ R₁ R₂ (nm) atom 21 CH₃ H CH₃ H —CH₃ —CH₃ 0.1461 −0.281 22 —CH₂CH₂CH₃H CH₂CH₂CH₃ H —CH₃ —CH₃ 0.1461 −0.283 23 *7 H H H —CH₃ —CH₃ 0.1443−0.299 24 —OCH₃ H H H —CH₃ —CH₃ 0.1445 −0.301 25 —OCH₂CH₃ H H H —CH₃—CH₃ 0.1445 −0.302 *1: The C—O bond distance represents the longer C—Obond distance of the two C—O bond distances in formula 1. Exemplifiedcompound 24-2: a bifunctional compound corresponding to Exemplifiedcompound 24

C—O bond distance: 0.1457 nm Charge of oxygen atom: −0.299 Exemplifiedcompound 24-3: a bifunctional compound corresponding to Exemplifiedcompound 24 (with an ether bond)

C—O bond distance: 0.1460 nm Charge of oxygen atom: −0.296 *7

[0088] Exemplified compounds 21-2 through 23-2 and 25-2 are cited asbifunctional compounds, which correspond to Exemplified compounds 21through 23 and 25, respectively, in the same manner as in Exemplifiedcompound 24-2, a bifunctional compound corresponding to Exemplifiedcompound 24. Exemplified compounds 21-3 through 23-3 and 25-3 are citedas bifunctional compounds (having an ether bond), which correspond toExemplified compounds 21 through 23 and 25 in the same manner as inExemplified compound 24-3, a bifunctional compound (having an etherbond) corresponding to Exemplified compound 24.

[0089] The above compounds can be synthesized according to the methoddescribed in Fourth item of “Kobunshikagaku to Yukikagaku tono KyacchiBoru” or a method described in literatures described later. For example,they are synthesized mainly according to the following scheme, but thesynthetic method is not specifically limited thereto.

[0090] Synthesis of Oxetane Compound I or I′ of Formula 1

[0091] Synthesis of Oxetane Compound III of Formula 6

[0092] 1. Hu Xianming, Richard M. Kellogg, Synthesis, 533-538, May(1955).

[0093] 2. A. O. Fitton, J. Hill, D. Ejane, R. Miller, Synth., 12, 1140(1987).

[0094] 3. Toshiro Imai and Sinya Nishida, Can. J. Chem. Vol. 59,2503-2509 (1981).

[0095] 4. Nobujiro Shimizu, Shintaro Yamaoka, and Yuho Tsuno, Bull.Chem. Soc. Jpn., 56, 3853-3854 (1983).

[0096] 5. Walter Fisher and Cyril A. Grob, Helv. Chim. Acta., 61, 2336(1978).

[0097] 6. Chem. Ber., 101, 1850 (1968).

[0098] 7. “Heterocyclic Compounds with Three- and Four-membered Rings”,Part Two, Chapter IX, Interscience Publishers, John Wiley & Sons, NewYork (1964).

[0099] 8. H. A. J. Curless, “Synthetic Organic Photochemistry”, Plenum,N.Y. (1984).

[0100] 9. M. Broun, Nachr. Chem. Tech. Lab., 33, 213 (1985).

[0101] 10. S. H. schroeter, J. Organic. Chem., 34, 5, 1151 (1969).

[0102] 11. D. r. Arnold, Adv. Photochem., 6, 301 (1968).

[0103] Next, a photo acid generator generating an acid on exposure oflight by will be explained. The photo acid generator herein referred toimplies a compound generating an acid on light irradiation.

[0104] As the photo acid generator, for example, compounds used in achemical amplification type photo resist or a light cationicpolymerization composition are used (Organic electronics materialseminar “Organic material for imaging” from Bunshin publishing house(1993), refer to page 187-192). Examples suitable for the presentinvention will be listed below.

[0105] Firstly, a B(C₆F₅)₄ ⁻, PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻, CF₃SO₃ ⁻ salt of anaromatic onium compound such as an aromatic diazonium, ammonium,iodonium, sulfonium, or phosphonium compound, can be listed.

[0106] Examples of the onium compounds used in the invention will beshown below.

[0107] Secondly, sulfone compounds, which generate sulfonic acid, can belisted. Examples thereof will be shown below.

[0108] Thirdly, halide compounds, which generate hydrogen halide, canalso be used. Example thereof will be shown below.

[0109] Fourthly, iron allene complexes can be listed.

[0110] It is preferred that an acid increasing agent is added to the inkof the invention, which is well known and which newly generates an acidby the acid generated by actinic ray irradiation, as disclosed in, forexample, JP-A Nos. H8-248561, and H9-034106. The addition of such anacid increasing agent can increase ink ejecting stability.

[0111] In the invention, known oxetane compounds other than the oxetanecompound I or I′ represented by formula (1) having an oxetane ring canbe used in combination. Combined use of the oxetane compound I in theinvention with an oxetane compound other than the oxetane compound inthe invention having one oxetane ring or an oxetane compound having twoor more oxetane rings is preferred in increasing strength of the curedink or adhesion of ink to recording material.

[0112] In the invention, the actinic ray curable composition of theinvention preferably contains a compound having an oxirane ring, inorder to increase further curability.

[0113] The compound having an oxirane ring in the invention is acompound having in the molecule at least one oxirane ring represented bythe following formula.

[0114] As such a compound, an epoxy resin is listed, which may be amonomer, an oligomer or a polymer.

[0115] The epoxy resins include an aromatic epoxide, an alicyclicepoxide, and an aliphatic epoxide, each being well known. Hereinafter,“epoxide” refers to an ethylene oxide monomer or an ethylene oxideoligomer. These compounds may be used singly or as an admixture of twoor more thereof.

[0116] Epoxy compounds include an aromatic epoxide, an alicyclic epoxideand an aliphatic epoxide, which will be explained below.

[0117] A preferable aromatic epoxide is a di- or poly-glycidyl ethermanufactured by a reaction of polyhydric phenol having at least onearomatic ring or of an alkylene oxide adduct thereof withepichlorohydrin, and includes, for example, such as di- or poly-glycidylether of bisphenol A or of an alkylene oxide adduct thereof, di- orpoly-glycidyl ether of hydrogenated bisphenol A or of an alkylene oxideadduct thereof and novolac type epoxy resin. Herein, alkylene oxideincludes such as ethylene oxide and propylene oxide.

[0118] An alicyclic epoxide is preferably a compound containingcyclohexene oxide or cyclopentene oxide obtained by epoxydizing acompound having at least one cycloalkane ring such as cyclohexene orcyclopentene by use of a suitable oxidizing agent such as hydrogenperoxide or a peracid.

[0119] A preferable aliphatic epoxide is such as di- or polyglycidylether of aliphatic polyhydric alcohol or of an alkylene oxide adductthereof; the typical examples include diglycidyl ether of alkyleneglycol, such as diglycidyl ether of ethylene glycol, diglycidyl ether ofpropylene glycol and diglycidyl ether of 1,6-hexane diol; polyglycidylether of polyhydric alcohol such as di- or triglycidyl ether of glycerinor of an alkylene oxide adduct thereof; and diglycidyl ether ofpolyalkylene glycol such as diglycidyl ether of polyethylene glycol orof an alkylene oxide adduct thereof and diglycidyl ether ofpolypropylene glycol or of an alkylene oxide adduct thereof. Herein,alkylene oxide includes such as ethylene oxide and propylene oxide.

[0120] Among these epoxides, aromatic epoxide and alicyclic epoxide arepreferable and alicyclic epoxide is specifically preferable, taking aquick curing property in consideration. In the invention, one kind ofepoxides described above alone may be utilized, and suitablecombinations of two or more kinds thereof may also be utilized.

[0121] The actinic ray curable ink of the invention contains pigment inaddition to the actinic ray curable composition as described above.

[0122] Pigments preferably utilized in the invention will be listedbelow:

[0123] C.I. Pigment Yellow-1, 3, 12, 13, 14, 17, 81, 83, 87, 95, 109,42,

[0124] C.I. Pigment Orange-16, 36, 38,

[0125] C.I. Pigment Red-5, 22, 38, 48:1, 48:2, 48:4, 49:1, 53:1, 57:1,63:1, 144, 146, 185, 101,

[0126] C.I. Pigment Violet-19, 23,

[0127] C.I. Pigment Blue-15:1, 15:3, 15:4, 4, 18, 60, 27, 29,

[0128] C.I. Pigment Green-7, 36,

[0129] C.I. Pigment White-6, 18, 21,

[0130] C.I. Pigment Black-7,

[0131] Further, in the invention, white ink is preferably utilized toincrease a covering power of colors with transparent base materials suchas a plastic film. It is preferable to utilize white ink, specificallyin light package printing and label printing, however, due to increaseof ejection amount, the using amount is naturally limited in respect tothe above-mentioned ejection stability, and generation of curl andwrinkles of a recording material.

[0132] To disperse the above-described pigment, for example, a ballmill, a sand mill, an attritor mill, a roll mill, an agitator, a Henshelmixer, a colloidal mixer, a ultrasonic homogenizer, a pearl mill, a wetjet mill, a paint shaker, etc. can be utilized. Further, a dispersantcan be added at dispersion of a pigment. As a dispersant, a polymerdispersant is preferably utilized and Solsperse Series manufactured byAvecia Co. is included. Further, as a dispersion aid, a synergistcorresponding to kinds of pigment can also be utilized. The dispersantand dispersion aid are preferably added in a range of from 1 to 50weight parts based on 100 parts of pigment. As a dispersion medium, asolvent or a polymerizable compound is utilized, however, the actinicray curable ink used in the invention is preferably an ink containing nosolvent, since curing is carried out immediately after the ink has beendeposited on recording material. When a solvent is left in the curedimage, there cause problems of deterioration of resistance againstsolvents and VOC of residual solvent. Therefore, as a dispersion medium,polymerizable compounds are used but a solvent not. Particularlymonomers having a lower viscosity among them are preferably used in viewof dispersion suitability.

[0133] In dispersion of a pigment, selection of a pigment, a dispersantand a dispersion medium, dispersion conditions and filtering conditionsare suitably set so as to make a mean particle diameter of a pigment ofpreferably from 0.08 to 0.5 μm and the maximum particle diameter of from0.3 to 10 μm and preferably from 0.3 to 3 μm. By this particle diametercontrol, it is possible to depress clogging of a head nozzle andmaintain stability of ink, as well as transparency and curingsensitivity of ink.

[0134] The pigment content of the actinic ray curable ink of theinvention is preferably from 1 to 10% by weight based on the total ink.

[0135] The content of the oxetane compound I or I′ in the actinic raycurable ink of the invention is preferably from 5 to 90% by weight, andmore preferably from 10 to 80% by weight, based on the total weight ofthe ink.

[0136] Various kinds of additives other than those explained above canbe added to the actinic ray curable ink of the invention. For example, asurfactant, a leveling additive, a matting agent, polyester type resin,polyurethane type resin, vinyl type resin, acryl type resin, rubber typeresin and wax series can be added to the ink when necessary. Further, inorder to increase storage stability, various basic compounds can beused. Examples of the basic compounds include a basic alkali metalcompound, a basic alkali earth metal compound and an organic basiccompound such as amine. The actinic ray curable ink of the invention maybe a radical and cationic polymerization hybrid curable ink furthercontaining a radical polymerization composition comprising a radicalpolymerization monomer and a radical initiator.

[0137] As a recording material used in the invention, besides ordinarynon-coated paper or coated paper, various non-absorptive plastics ortheir films, which are used in a so-called light packaging, can beutilized. Examples of the plastic films include for example, a PET film,an OPS film, an OPP film, an ONy film, a PVC film, a PE film and a TACfilm. As plastic films other than these, polycarbonate, acryl resin,ABS, polyacetal, PVA and a rubber series can be utilized. A metal seriesand a glass series are also applicable. The constitution of theinvention becomes more effective especially when an image is formedparticularly on a PET film, an OPS film, an OPP film, an ONy film and aPVC film, which are capable of thermally shrinking, of these recordingmaterials. Generally, these recording materials are liable to cause curland deformation of film due to such as curing shrinkage or heatgeneration at curing reaction of ink, and, in addition, a formed inklayer is hard to follow shrinkage of the materials.

[0138] Plastic films greatly differ in surface energy depending on thekinds, and heretofore, there has been a problem in that the ink dotdiameter after ink deposition on recording material varies depending onthe kinds of the recording materials. The constitution of the inventioncan form an image with high precision on recording materials having asurface energy of from 35 to 60 mN/m, the recording materials rangingfrom those having a low surface energy such as an OPP or OPS film tothose having a relatively high surface energy such as a PET film.

[0139] In the invention, a long length roll (web) of a recordingmaterial is advantageously utilized in respect to a cost of a recordingmaterial such as a packaging cost and a manufacturing cost, anefficiency of print preparation and applicability to variety of printsizes.

[0140] An image forming method of the invention will be explained.

[0141] In the image forming method in the invention, it is preferredthat the ink described above be ejected onto a recording materialaccording to an ink jet recording method, and then cured by irradiationof actinic ray such as UV ray. (Thickness of ink layer formed after inkis ejected onto recording material)

[0142] In the invention, the thickness of an ink layer, after ink hasbeen ejected onto recording material and cured by actinic rayirradiation, is preferably from 2 to 20 μm. In actinic ray curable inkjet recording in the field of screen printing, the total thickness ofthe ink is at present over 20 μm. Ink ejecting to give an excessivelayer thickness is not preferred in the field of flexible packageprinting where a thin plastic film is used as a recording material,because problems are caused in that stiffness and texture of printedmatter vary, in addition to problems of the aforementioned curl andwrinkles of recording material.

[0143] Herein, the thickness of ink layer refers to a maximum thicknessof the ink layer deposited on recording material. This applies to asingle color ink layer, and an overlapped layer of two different color(secondary color) inks, three different color inks or four differentcolor inks (including white ink as a base ink), which are formed onrecording material according to an ink jet recording process.

[0144] (Conditions of Ink Ejection)

[0145] As conditions of ink ejection, ink ejection is preferablyperformed while a recording head and ink are heated at from 35 to 100°C. in respect to ejection stability. Since actinic ray curable ink showsa large viscosity variation width depending on temperature variation andwhich in turn significantly influences a liquid droplet size and aliquid droplet ejection speed resulting in deterioration of imagequality, it is required to keep an ink temperature constant whileraising the ink temperature. A control width of ink temperature is a settemperature ±5° C., preferably a set temperature ±2° C. and furthermorepreferably a set temperature ±1° C.

[0146] In the ink of the invention, the content of components in theactinic ray curable ink of the invention is preferably adjusted to givean ink viscosity at 25° C. of from 7 to 50 mPa.s in view of ink ejectionstability.

[0147] In the invention, a droplet volume of the photo-curable inkejected from nozzles of the ink jet recording head is preferably 2 to 15pl.

[0148] The droplet volume of the ink has to be in the range describedabove to form images with high resolution, however, this droplet volumetends to lower the aforementioned ejection stability. In the invention,even when a small droplet volume such as 2 to 15 pl is ejected, ejectionstability is improved, and images with high resolution can be formed.

[0149] (Actinic ray Irradiation Condition after Ink has been Ejectedonto Recording Material)

[0150] In an image recording method of the invention, it is preferredthat actinic ray is irradiated 0.001 to 2.0 seconds after ink has beenejected on recording material, and it is more preferred that actinic rayis irradiated 0.001 to 1.0 second after ink has been ejected onrecording material. It is specifically important that the irradiationtiming be as early as possible in order to form an image with highresolution.

[0151] As an actinic ray irradiation method, a basic method is disclosedin JP-A No. 60-132767, in which light sources are provided at the bothsides of a head unit where a head and a light are scanned in a shuttlemode. Irradiation is performed in a certain time interval after ink hasbeen ejected onto recording material. Further, curing is completed byanother light source which is not driven. As a light irradiation method,a method utilizing optical fiber, and a method in which collimated lightsource is reflected by a mirror provided on the side surface of a headunit and UV light (ultraviolet light) is irradiated on a recordingportion are disclosed in U.S. Pat. No. 6,145,979. In an image formingmethod of the invention, any of these irradiation methods can beutilized.

[0152] Further, a method is also a preferable embodiment, in whichactinic ray irradiation is divided into two steps; firstly, a firstactinic ray irradiation is carried between the period from 0.001 to 2.0seconds after ink was deposited on recording material by theabove-described method and further a second actinic ray irradiation iscarried after printing has been completed. Shrinkage of recordingmaterials caused at the time of ink curing can be depressed by dividingactinic ray irradiation into two steps.

[0153] Heretofore, in a UV ink jet method, it has been usual to utilizea light source of high illuminance having a power exceeding 1 kW·hr inorder to minimize widening of dots and bleeding-out caused after inkdeposition on recording material. However, particularly in such as ashrink label, utilizing the light sources makes shrinkage of a recordingmaterial too large to be used practically at present.

[0154] In the invention, an actinic ray having a maximum illuminance ina wavelength range from 280 to 320 nm is preferably used, and even whena light source a power exceeding 1 kW·hr is used, images with highresolution can be formed, and shrinkage of a recording material is inthe permissible range.

[0155] In the invention, the power of light sources irradiating anactinic ray is preferably less than 1 kW·hr. Examples of the lightsources having a power of less than 1 kW·hr include a fluorescent lamp,a cold cathode tube and an LED, but are not limited thereto.

[0156] An ink jet recording apparatus (hereinafter also referred to as arecording apparatus) in the invention will be explained.

[0157] Next, the recording apparatus in the invention will be explainedsuitably in reference to a drawing. Herein, the recording apparatus ofthe drawing is only an embodiment of a recording apparatus of theinvention, and a recording apparatus of the invention is not limited tothe drawing.

[0158]FIG. 1 is a front view illustrating a main constitution of arecording apparatus of the invention. Recording apparatus 1 is equippedwith head carriage 2, recording head 3, irradiation means 4 and platenportion 5. In recording apparatus 1, platen portion 5 is arranged underrecording material P. Platen portion 5 has a UV ray absorbing function,and absorbs extra UV ray having passed through recording material P. Asa result, images with high resolution can be reproduced quite stably.

[0159] Recording material P is guided by guide member 6 to be moved tothe back side from the front side in FIG. 1 by operation of a transportmeans (not illustrated). Scan of recording head 3 held in head carriage2 is made by reciprocating head carriage 2 in Y direction in FIG. 1according to a head scanning means (not illustrated).

[0160] Head carriage 2 is provided over recording material P, and storesrecording heads 3 described below with the ejection outlet 31 arrangeddownward, the number of recording heads 3 corresponding to the number ofcolor inks used in an ink image printed on recording material. Headcarriage 2 is provided in the main body of recording apparatus 1 so asto reciprocate in Y direction in FIG. 1 by a drive of a head scanningmeans.

[0161] Herein, FIG. 1 illustrates that head carriage 2 is supposed tostore recording heads 3 of white (W), yellow (Y), magenta (M), cyan (C),black (K), light yellow (Ly), light magenta (Lm), light cyan (Lc), lightblack (Lk) and white (W), however, the number of recording heads 3stored in head carriage 2 in practical operation is suitably determined.

[0162] Recording head 3 ejects an actinic ray curable ink (for example,UV curable ink) to be supplied by means of an ink supplying means (notillustrated) from its ejection outlets onto recording material P byaction of plural ejecting means (not illustrated) equipped in therecording apparatus. A UV ink to be ejected by recording head 3 iscomprised of a colorant, a polymerizing monomer, an initiator, etc., andis cured by cross-linking and polymerization initiated by UV irradiationof an initiator as a catalyst.

[0163] Recording head 3 ejects UV ink as an ink droplet onto apre-determined region (a region capable of receiving the ink) ofrecording material P while the scan of the head is made in which thehead moves from one edge to another of the recording material in a Ydirection in FIG. 1 by drive of the head scanning means, whereby the UVink is deposited on that region of the recording material.

[0164] The above scan is suitably made several times to eject UV inkonto one region of recording material. After that, while the recordingmaterial P is transported from the front side to the back side in FIG. 1by transport means and the scan of the recording head 3 is again made bythe head scan means, UV ink is ejected from the recording head onto thenext region of the back side in FIG. 1 of recording material, which isadjacent to the one region on which the UV ink has been ejected.

[0165] The above operation is repeated, whereby the UV ink is ejectedfrom recording head 3 employing the head scan means and the transportmeans to form an image comprised of aggregates of UV ink droplets onrecording material P.

[0166] Irradiation means 4 is equipped with a UV lamp which emitsultraviolet ray with a specific wavelength region at a stable exposureenergy and a filter which transmits ultraviolet ray with a specificwavelength. Herein, Examples of the UV lamp include a mercury lamp, ametal halide lamp, an eximer laser, a UV laser, a cold cathode tube, ablack light, and an LED, and a metal halide lamp tube, a cold cathodetube, a mercury lamp tube and a black light, having a band-shape, arepreferable. Specifically a cold cathode tube and a black light whichemit a 365 nm ultraviolet ray are preferable, which can preventbleeding-out, efficiently control a dot diameter, and reduce wrinkles oncuring. Utilizing a black light as a radiation source of irradiationmeans 4 reduces a manufacturing cost of irradiation means 4 for UV inkcuring.

[0167] Irradiation means 4 has the possible largest size which can beinstalled in the recording apparatus 1 (an ink jet printer) or theirradiation region of the irradiation means 4 is larger than the largestregion of recording material, onto which UV ink is ejected by one timescan of recording head 3 driven by a head scan means.

[0168] Irradiation means 4 is arranged by being fixed in nearly parallelwith recording material 4 at the both sides of head carriage 2.

[0169] As described above, in order to adjust illuminance at an inkejecting portion, it is natural to light-shield whole recording head 3,and, in addition, it is effective to make distance h2 between inkejection outlet 31 of recording head 3 and recording material P longerthan distance h1 between irradiation means 4 and recording material P(h1<h2) or to make distance d between recording head 3 and irradiationmeans 4 long (to make d large). Further, it is furthermore preferable toprovide bellows structure 7 between recording head 3 and irradiationmeans 4.

[0170] Herein, wavelength of ultraviolet ray irradiated throughirradiation means 4 can be suitably changed by changing a UV lamp or afilter, which is installed in irradiation means 4.

EXAMPLES

[0171] The invention will be explained according to the followingexamples, however, the invention is not specifically limited therto.

Example 1

[0172] <<Preparation of Ink>>

[0173] Ink set 1 (Comparative) having the constitution as shown in Table2 and Ink sets 2 through 5 (Inventive) having the constitution as shownin Tables 3 through 6 were prepared. TABLE 2 Ink Composition (% byweight) Thermal Photopolymerizable base compound Acid generating PhotoKinds Colorant Oxetane compound increasing agent acid Sensitizing ofAdded Comparative agent Thermal generator dye ink Kinds amount compound1 OXT-221 Acpress 11M base 1 CI-5102 CS-7001 Ink set K Colorant 5.0 41.045.0 1.0 0.01 5.0 3.0 1 1 (Comp.) C Colorant 2.5 40.5 50.0 1.0 0.01 3.03.0 2 M Colorant 3.0 40.0 50.0 1.0 0.01 3.0 3.0 3 Y Colorant 2.5 40.550.0 1.0 0.01 3.0 3.0 4 W Colorant 5.0 43.0 45.0 1.0 0.01 3.0 3.0 5 LkColorant 0.6 42.4 50.0 1.0 0.01 3.0 3.0 1 Lc Colorant 0.8 42.3 50.0 1.00.01 3.0 3.0 2 Lm Colorant 0.6 42.4 50.0 1.0 0.01 3.0 3.0 3 Ly Colorant0.2 42.8 50.0 1.0 0.01 3.0 3.0 4

[0174] TABLE 3 Ink Composition (% by weight) Thermal Photopolymerizablebase compound Acid generating Photo Kinds Colorant Oxetane compoundincreasing agent acid Sensitizing of Added Exemplified agent Thermalgenerator dye ink Kinds amount compound 7 OXT-221 Acpress 11M base 1CI-5102 CS-7001 Ink set K Colorant 5.0 41.0 45.0 1.0 0.01 5.0 3.0 2 1(Inv.) C Colorant 2.5 40.5 50.0 1.0 0.01 3.0 3.0 2 M Colorant 3.0 40.050.0 1.0 0.01 3.0 3.0 3 Y Colorant 2.5 40.5 50.0 1.0 0.01 3.0 3.0 4 WColorant 5.0 43.0 45.0 1.0 0.01 3.0 3.0 5 Lk Colorant 1.3 41.7 50.0 1.00.01 3.0 3.0 1 Lc Colorant 0.6 42.4 50.0 1.0 0.01 3.0 3.0 2 Lm Colorant0.8 42.2 50.0 1.0 0.01 3.0 3.0 3 Ly Colorant 0.6 42.4 50.0 1.0 0.01 3.03.0 4

[0175] TABLE 4 Ink Composition (% by weight) Photopolymerizable Thermalcompound Acid base Photo Oxetane increasing generating acid SensitizingKinds Colorant Epoxy compound agent Basic agent generator dye of Addedcompound Exemplified Acpress compound Thermal Initiator CS- ink Kindsamount DAIMIC compound 1 OXT-212 11M *1 base 2 1 7102 Ink set K Colorant5.0 15.0 46.1 24.8 3.0 0.01 0.1 5.0 1.0 3 1 (Inv.) C Colorant 2.5 10.048.1 32.3 3.0 0.01 0.1 3.0 1.0 2 M Colorant 3.0 10.0 48.1 31.8 3.0 0.010.1 3.0 1.0 3 Y Colorant 2.5 10.0 48.1 32.3 3.0 0.01 0.1 3.0 1.0 4 WColorant 5.0 15.0 46.1 26.8 3.0 0.01 0.1 3.0 1.0 5 Lk Colorant 1.3 10.047.5 34.2 3.0 0.01 0.1 3.0 1.0 1 Lc Colorant 0.6 10.0 48.2 34.1 3.0 0.010.1 3.0 1.0 2 Lm Colorant 0.8 10.0 48.0 34.2 3.0 0.01 0.1 3.0 1.0 3 LyColorant 0.6 10.0 47.6 34.6 3.0 0.01 0.1 3.0 1.0 4

[0176] TABLE 5 Ink Composition (% by weight) Photopolymerizable compoundThermal Oxetane Acid base compound increasing generating Photo KindsColorant Epoxy Exemplified agent Basic agent acid Sensitizing of Addedcompound compound OXT- Compound compound Thermal generator dye ink Kindsamount EPOLEAD 14 221 1 *2 base 1 SP152 DBA Ink set K Colorant 5.0 15.840.0 30.0 3.0 0.1 0.1 5.0 1.0 4 1 (Inv.) C Colorant 2.5 21.8 40.0 30.01.5 0.1 0.1 3.0 1.0 2 M Colorant 3.0 21.3 40.0 30.0 1.5 0.1 0.1 3.0 1.03 Y Colorant 2.5 21.8 40.0 30.0 1.5 0.1 0.1 3.0 1.0 4 W Colorant 5.019.3 40.0 30.0 1.5 0.1 0.1 3.0 1.0 5 Lk Colorant 1.3 23.1 40.0 30.0 1.50.1 0.1 3.0 1.0 1 Lc Colorant 0.6 23.7 40.0 30.0 1.5 0.1 0.1 3.0 1.0 2Lm Colorant 0.8 23.6 40.0 30.0 1.5 0.1 0.1 3.0 1.0 3 Ly Colorant 0.623.7 40.0 30.0 1.5 0.1 0.1 3.0 1.0 4

[0177] TABLE 6 Ink Composition (% by weight) Thermal basePhotopolymerizable compound Acid generating Oxetane compound increasingagent Kinds Epoxy Exemplified Exemplified agent Basic Thermal ofColorant compound compound compound OXT- Compound compound base **3 **5ink Kinds **2 Adecasizer 7-3 7 211 2 *1 2 **4 DBA **1 K Colorant 5.0 8.420.0 35.0 25.0 3.0 0.01 0.1 2.5 1.0 1 C Colorant 2.5 10.9 15.0 40.0 25.03.0 0.01 0.1 2.5 1.0 2 M Colorant 3.0 10.4 15.0 40.0 25.0 3.0 0.01 0.12.5 1.0 3 Y Colorant 2.5 10.9 15.0 40.0 25.0 3.0 0.01 0.1 2.5 1.0 4 WColorant 5.0 8.4 20.0 35.0 25.0 3.0 0.01 0.1 2.5 1.0 5 Lk Colorant 1.312.1 15.0 40.0 25.0 3.0 0.01 0.1 2.5 1.0 1 Lc Colorant 0.6 12.8 15.040.0 25.0 3.0 0.01 0.1 2.5 1.0 2 Lm Colorant 0.8 12.6 15.0 40.0 25.0 3.00.01 0.1 2.5 1.0 3 Ly Colorant 0.6 12.8 15.0 40.0 25.0 3.0 0.01 0.1 2.51.0 4

[0178] Details of each compound in the inks described in Tables 2 to 6are as follows.

[0179] K: deep black ink

[0180] C: deep cyan ink

[0181] M: deep magenta ink

[0182] Y: deep yellow ink

[0183] Lk: light black ink

[0184] Lc: light cyan ink

[0185] Lm: light magenta ink

[0186] Ly: light yellow ink

[0187] Colorant 1: C.I. pigment Black-7

[0188] Colorant 2: C.I. pigment Blue-15:3

[0189] Colorant 3: C.I. pigment Red-57:1

[0190] Colorant 4: C.I. pigment Yellow-13

[0191] Colorant 5: Titanium oxide (anatage type, average particlediameter: 0.20 μm)

[0192] Comparative compound 1: the C—O bond distance in theinvention=0.1463 nm

[0193] OXT-211 (oxetane compound produced by Toa Gosei Kagaku Co.,Ltd.): the C—O bond distance in the invention=0.1456 nm

[0194] OXT-212 (oxetane compound produced by Toa Gosei Kagaku Co.,Ltd.): the C—O bond distance in the invention=0.1455 nm

[0195] OXT-221 (oxetane compound produced by Toa Gosei Kagaku Co.,Ltd.): the C—O bond distance in the invention=0.1456 nm

[0196] DAIMIC: DAIMIC S300K epoxidated soy bean oil produced by DaicelKagaku Co., Ltd.

[0197] EPOLEAD: EPOLEAD PB3600 epoxidated polybutadiene produced byDaicel Kagaku Co., Ltd.

[0198] Adecasizer: Adecasizer 0-130 epoxidated soy bean oil (admitted byFDA) produced by Asahi Denka Kogyo Co., Ltd.

[0199] Acpress 11: produced by Nippon Chemics Co., Ltd.

[0200] Acpress 11M: produced by Nippon Chemics Co., Ltd.

[0201] CGI552: produced by Ciba Specialty Chemicals Co., Ltd.

[0202] CS-7001: Naphthalene derivative, produced by Nippon Soda Co.,Ltd.

[0203] CS-7102: Anthracene derivative, produced by Nippon Soda Co., Ltd.

[0204] SP152: produced by Asahi Denka Kogyo Co., Ltd.

[0205] DBA: produced by Kawasaki Kasei Kogyo Co., Ltd.

[0206] Basic compound *1: N-ethyldiethanolamine

[0207] Basic compound *2: Tributylamine

[0208] Viscosity of each of the inks of the ink sets prepared above isas follows: Inks in Ink set 1: 18 mPa · s Inks in Ink set 2: 18 mPa · sInks in Ink set 3: 25 mPa · s Inks in Ink set 4: 30 mPa · s Inks in Inkset 5: 25 mPa · s

[0209] <<Ink Jet Image Forming Method>>

[0210] An ink jet recording image was formed as follows.

[0211] Each ink set prepared as above was mounted on an ink jetrecording apparatus as shown in FIG. 1 equipped with piezo-type ink jetnozzles, and image recording described later was performed continuouslyon each of 600 mm wide and 1000 m long recording materials havingsurface energy as shown in Table 7. An ink supply system is comprised ofan ink tank, a supply pipe, a pre-chamber ink tank directly before ahead, piping incorporating a filter, and a piezo-head, and the portionfrom a pre-chamber tank to a head was heat-insulated and heated at 50°C. The piezo-head being driven so as to eject ink with a droplet volumeof from 2 to 15 pl at a resolution of 720 dpi×720 dpi to form amulti-sized dot image on recording material, the ink was continuouslyejected. Curing was carried out after the ink was deposited on therecording material under the irradiation conditions as shown in Table 7.Curing was carried out 0.2 seconds after ink deposition with respect tosamples 1 through 8, and 0.1 seconds after ink deposition with respectto samples 9 through 20. The thickness of the resulting ink layer wasmeasured to be in a range of from 2.3 to 13 μm. Herein, dpi represents adot number per 2.54 cm.

[0212] The above ink jet image recording were carried out under threerecording circumstances, at 10° C. and 20% RH, at 25° C. and 50% RH, andat 32° C. and 80% RH, according to the image forming method describedabove.

[0213] In Table 7, abbreviation of each of the recording materials is asfollows:

[0214] OPP: oriented polypropyrene

[0215] PET: polyethylene terephthalate

[0216] Shrink OPS: Oriented polystyrene for use of shrinkage availableon the market

[0217] Details of the light sources shown in Table 7 are as follows.

[0218] Light source 1: 120 W/cm metal halide lamp (MAL 400NL, producedby Nippon Denchi Co., Ltd., Output: 3 kW)

[0219] Light source 2: a cold cathode tube (produced by HYBECK Co.,Ltd., Consumption power: less than 1 kW·hr)

[0220] Light source 3: LED (special order product produced by NichiaKagaku Kogyo Co., Ltd., Consumption power: less than 1 kW·hr)

[0221] Details of the irradiation methods shown in Table 7 are asfollows.

[0222] Irradiation method A: irradiation from both sides of a recordinghead employing a linear light source

[0223] Irradiation method B: irradiation from both sides of a recordinghead employing four 310 nm linear light sources and four 56 nm linearlight sources

[0224] Irradiation method C: irradiation from both sides of a recordinghead employing twenty LED sources

[0225] Thus, samples 1 through 20 as shown in Table 7 were obtained.TABLE 7 Irradiation condition on the recording Light source materialsurface used Recording materials Kinds *Peak Peak Ink Surface of wave-Maximum wave- Output Sample set energy light Irradiation lengthilluminance length power No. No. Kinds (mN/m) source method (nm)(mW/cm²) (nm) (mW/cm²) Remarks 1 1 OPP 38 1 A 365 650 365 180 Comp. 2 1PET 53 1 A 365 650 365 180 Comp. 3 1 **OPS 39 1 A 365 650 365 180 Comp.4 1 ***paper *1 1 A 365 650 365 180 Comp. 5 2 OPP 38 1 A 365 650 365 180Inv. 6 2 PET 53 1 A 365 650 365 180 Inv. 7 2 **OPS 39 1 A 365 650 365180 Inv. 8 2 ***paper *1 1 A 365 650 365 180 Inv. 9 3 OPP 38 2 B 365/31015/10 365/310 50/33 Inv. 10 3 PET 53 2 B 365/310 15/10 365/310 50/33Inv. 11 3 **OPS 39 2 B 365/310 15/10 365/310 50/33 Inv. 12 3 ***paper *12 B 365/310 15/10 365/310 50/33 Inv. 13 4 OPP 38 2 B 365/310 15/10365/310 50/33 Inv. 14 4 PET 53 2 B 365/310 15/10 365/310 50/33 Inv. 15 4**OPS 39 2 B 365/310 15/10 365/310 50/33 Inv. 16 4 ***paper *1 2 B365/310 15/10 365/310 50/33 Inv. 17 5 OPP 38 3 C 380  40 380  80 Inv. 185 PET 53 3 C 380  40 380  80 Inv. 19 5 **OPS 39 3 C 380  40 380  80 Inv.20 5 ***paper *1 3 C 380  40 380  80 Inv.

[0226] <Evaluation of Ink Jet Recording Images>

[0227] The resulting ink jet recording images under the three recordingcircumstances described above were evaluated according to the followingevaluation methods.

[0228] (Character Quality)

[0229] 6-point MS Minchyo (Ming-style) font characters were recorded atan intended density employing inks Y, M, C and K, and the resultingcharacters were evaluated for smoothness through a magnifying glassaccording to the following criteria. Herein, MS (Micro Soft™ Minchyo(Ming-style) font is one of the Japanese fonts for printing.

[0230] A: No roughness was observed.

[0231] B: Slight roughness was observed.

[0232] C: Roughness was observed, however, the resulting characters werelegible, but at the lowest practical level.

[0233] D: Significant roughness was observed, and the resultingcharacters were scratchy, and were not acceptable for practical use.

[0234] (Color Contamination (or Bleeding-Out))

[0235] One dot of each of inks Y, M, C and K was recorded at 720 dpi tobe adjacent to each other, and the resulting adjacent dots wereevaluated for color contamination (or bleeding-out) through a magnifyingglass according to the following criteria.

[0236] A: The shapes of adjacent dots where circular, with nobleeding-out observed.

[0237] B: The shapes of adjacent dots were nearly circular with littlebleeding-out observed.

[0238] C: Adjacent dots showed some bleeding-out, and the dots wereslightly deformed, but at the lowest practical level.

[0239] D: Adjacent dots showed bleeding-out and contaminated each other,which was not acceptable for practical use.

[0240] The results are shown in Table 8. TABLE 8 Recording Circumstances10° C., 20% RH 25° C., 50% RH 32° C., 80% RH Sample Character ColorCharacter Color Character Color No. Quality Contamination QualityContamination Quality Contamination Remarks 1 B B C B D C Comp. 2 B B BC D D Comp. 3 B B C B D D Comp. 4 B B B C C D Comp. 5 B B B B C B Inv. 6B B B B B C Inv. 7 B B B B C B Inv. 8 A A A B B B Inv. 9 B B B B C BInv. 10 B A B A B A Inv. 11 A A A A A A Inv. 12 A A A A A A Inv. 13 B AB A B A Inv. 14 A A A A A B Inv. 15 A A A A A B Inv. 16 A B A B A B Inv.17 B A B A B A Inv. 18 A A A A A B Inv. 19 A A A A A B Inv. 20 A A A A AA Inv.

[0241] As is apparent from Table 8 above, the image recording method ofthe invention, which is carried out employing the inventive ink setscomprising the actinic ray curable composition of the invention, formsan image with high resolution with an excellent character quality, andexhibits no color contamination on various kinds of recording materials.

Example 2

[0242] Ink set 21 (Comparative) having the constitution as shown inTable 2-2 and Ink sets 22 through 25 (Inventive) having the constitutionas shown in Tables 2-3 through 2-6 were prepared. TABLE 2-2 InkComposition (% by weight) Photopolymerizable compound Acid KindsColorant Oxetane compound increasing Photo acid Sensitizing of AddedComparative agent generator dye ink Kinds amount compound 1 OXT-221Acpress 11M CGI552 CS-7001 Ink set K Colorant 5.0 41.0 45.0 1.0 5.0 3.021 1 (Comp.) C Colorant 2.5 40.5 50.0 1.0 3.0 3.0 2 M Colorant 3.0 40.050.0 1.0 3.0 3.0 3 Y Colorant 2.5 40.5 50.0 1.0 3.0 3.0 4 W Colorant 5.043.0 45.0 1.0 3.0 3.0 5 Lk Colorant 0.6 42.4 50.0 1.0 3.0 3.0 1 LcColorant 0.8 42.3 50.0 1.0 3.0 3.0 2 Lm Colorant 0.6 42.4 50.0 1.0 3.03.0 3 Ly Colorant 0.2 42.8 50.0 1.0 3.0 3.0 4

[0243] TABLE 2-3 Ink Composition (% by weight) Photopolymerizablecompound Acid Kinds Colorant Oxetane compound increasing Photo acidSensitizing of Added Exemplified agent generator dye ink Kinds amountcompound 23 OXT-221 Acpress 11M CGI552 CS-7001 Ink set K Colorant 5.041.0 45.0 1.0 5.0 3.0 22 1 (Inv.) C Colorant 2.5 40.5 50.0 1.0 3.0 3.0 2M Colorant 3.0 40.0 50.0 1.0 3.0 3.0 3 Y Colorant 2.5 40.5 50.0 1.0 3.03.0 4 W Colorant 5.0 43.0 45.0 1.0 3.0 3.0 5 Lk Colorant 1.3 41.8 50.01.0 3.0 3.0 1 Lc Colorant 0.6 42.4 50.0 1.0 3.0 3.0 2 Lm Colorant 0.842.3 50.0 1.0 3.0 3.0 3 Ly Colorant 0.6 42.4 50.0 1.0 3.0 3.0 4

[0244] TABLE 2-4 Ink Composition (% by weight) Photopolymerizablecompound Oxetane Acid Photo compound increasing acid Kinds ColorantEpoxy Exemplified agent generator Sensitizing of Added compound compoundOXT- Acpress Initiator dye ink Kinds amount DAIMIC 24 212 11M 1 CS-7102Ink set K Colorant 5.0 15.0 46.1 24.9 3.0 5.0 1.0 23 1 (Inv.) C Colorant2.5 10.0 48.1 32.4 3.0 3.0 1.0 2 M Colorant 3.0 10.0 48.1 31.9 3.0 3.01.0 3 Y Colorant 2.5 10.0 48.1 32.4 3.0 3.0 1.0 4 W Colorant 5.0 15.046.1 26.9 3.0 3.0 1.0 5 Lk Colorant 1.3 10.0 47.5 34.3 3.0 3.0 1.0 1 LcColorant 0.6 10.0 48.2 34.2 3.0 3.0 1.0 2 Lm Colorant 0.8 10.0 48.0 34.33.0 3.0 1.0 3 Ly Colorant 0.6 10.0 47.6 34.8 3.0 3.0 1.0 4

[0245] TABLE 2-5 Ink Composition (% by weight) Photopolymerizablecompound Oxetane compound Acid Photo Kinds Colorant Epoxy Exemplifiedincreasing acid Sensitizing of Added compound compound OXT- agentgenerator dye ink Kinds amount EPOLEAD 24-2 212 Compound 1 SP152 DBA Inkset K Colorant 5.0 16.0 40.0 30.0 3.0 5.0 1.0 24 1 (Inv.) C Colorant 2.522.0 40.0 30.0 3.0 3.0 1.0 2 M Colorant 3.0 21.0 40.0 30.0 3.0 3.0 1.0 3Y Colorant 2.5 22.0 40.0 30.0 3.0 3.0 1.0 4 W Colorant 5.0 19.5 40.030.0 3.0 3.0 1.0 5 Lk Colorant 1.3 23.3 40.0 30.0 3.0 3.0 1.0 1 LcColorant 0.6 23.9 40.0 30.0 3.0 3.0 1.0 2 Lm Colorant 0.8 23.8 40.0 30.03.0 3.0 1.0 3 Ly Colorant 0.6 23.9 40.0 30.0 3.0 3.0 1.0 4

[0246] TABLE 2-6 Ink Composition (% by weight) Photopolymerizablecompound Acid Photo Oxetane compound increasing acid Kinds ColorantEpoxy Exemplified Exemplified agent generator Sensitizing of Addedcompound compound compound OXT- Compound Initiator dye ink Kinds amountAdecasizer 24-3 24 211 2 2 DBA Ink set K Colorant 5.0 8.4 20.0 35.0 25.03.0 2.5 1.0 25 1 (Inv.) C Colorant 2.5 10.9 15.0 40.0 25.0 3.0 2.5 1.0 2M Colorant 3.0 10.4 15.0 40.0 25.0 3.0 2.5 1.0 3 Y Colorant 2.5 10.915.0 40.0 25.0 3.0 2.5 1.0 4 W Colorant 5.0 8.4 20.0 35.0 25.0 3.0 2.51.0 5 Lk Colorant 1.3 12.1 15.0 40.0 25.0 3.0 2.5 1.0 1 Lc Colorant 0.612.8 15.0 40.0 25.0 3.0 2.5 1.0 2 Lm Colorant 0.8 12.6 15.0 40.0 25.03.0 2.5 1.0 3 Ly Colorant 0.6 12.8 15.0 40.0 25.0 3.0 2.5 1.0 4

[0247] Details of the compounds used in the inks in Tables 2-2 to 2-6are as follows.

[0248] Comparative compound 1: Charge of the oxygen atom=−0.279, the C—Obond distance in the invention=0.1463 nm

[0249] OXT-211 (oxetane compound produced by Toa Gosei Kagaku Co.,Ltd.): Charge of the oxygen atom=−0.275, the C—O bond distance in theinvention=0.1456 nm

[0250] OXT-212 (oxetane compound produced by Toa Gosei Kagaku Co.,Ltd.): Charge of the oxygen atom=−0.280, the C—O bond distance in theinvention=0.1455 nm

[0251] OXT-221 (oxetane compound produced by Toa Gosei Kagaku Co.,Ltd.): Charge of the oxygen atom=−0.275, the C—O bond distance in theinvention=0.1456 nm

[0252] CGI552: produced by Ciba Specialty Chemicals Co., Ltd.

[0253] Viscosity of each of the inks of the ink sets prepared above isas follows: Inks in Ink set 21: 17 mPa · s Inks in Ink set 22: 17 mPa ·s Inks in Ink set 23: 25 mPa · s Inks in Ink set 24: 28 mPa · s Inks inInk set 25: 28 mPa · s

[0254] <<Ink Jet Image Forming Method>>

[0255] An ink jet recording image was formed as follows.

[0256] Each ink set prepared as above was mounted on an ink jetrecording apparatus as shown in FIG. 1 equipped with piezo-type ink jetnozzles, and image recording described later was performed continuouslyon each of 600 mm wide and 1000 m long recording materials havingsurface energy as shown in Table 2-7. An ink supply system is comprisedof an ink tank, a supply pipe, a pre-chamber ink tank directly before ahead, piping incorporating a filter, and a piezo-head, and the portionfrom a pre-chamber tank to a head was heat-insulated and heated at 50°C. The piezo-head being driven so as to eject ink with a droplet volumeof from 2 to 15 pl at a resolution of 720 dpi×720 dpi to form amulti-sized dot image on recording material, the ink was continuouslyejected. Curing was carried out after the ink was deposited on therecording material under the irradiation conditions as shown in Table2-7. Curing was carried out 0.2 seconds after ink deposition withrespect to samples 21 through 28, and 0.1 seconds after ink depositionwith respect to samples 29 through 40. The thickness of the resultingink layer was measured to be in a range of from 2.3 to 13 μm.

[0257] The above ink jet image recording were carried out under threerecording circumstances, at 10° C. and 20% RH, at 25° C. and 50% RH, andat 32° C. and 80% RH, according to the image forming method describedabove.

[0258] Details of the light sources shown in Table 2-7 are as follows.

[0259] Light source 1: 120 W/cm metal halide lamp (MAL 400NL, producedby Nippon Denchi Co., Ltd., Output: 3 kW)

[0260] Light source 2: a cold cathode tube (produced by HYBECK Co.,Ltd., Consumption power: less than 1 kW·hr)

[0261] Light source 3: LED (special order product produced by NichiaKagaku Kogyo Co., Ltd., Consumption power: less than 1 kW·hr)

[0262] Details of the irradiation methods shown in Table 2-7 are asfollows.

[0263] Irradiation method A: irradiation from both sides of a recordinghead employing a linear light source

[0264] Irradiation method B: irradiation from both sides of a recordinghead employing four 310 nm linear light sources and four 365 nm linearlight sources

[0265] Irradiation method C: irradiation from both sides of a recordinghead employing twenty LED sources

[0266] Thus, samples 2-1 through 2-20 as shown in Table 2-7 wereobtained. TABLE 2-7 Irradiation condition on the recording Light sourcematerial surface used Recording materials Kinds *Peak *Peak Ink Surfaceof wave- Maximum wave- Output Sample set energy light Irradiation lengthilluminance length power No. No. Kinds (mN/m) source method (nm)(mW/cm²) (nm) (mW/cm²) Remarks 21 21 OPP 38 1 A 365 650 365 180 Comp. 2221 PET 53 1 A 365 650 365 180 Comp. 23 21 **OPS 39 1 A 365 650 365 180Comp. 24 21 ***paper *1 1 A 365 650 365 180 Comp. 25 22 OPP 38 1 A 365650 365 180 Inv. 26 22 PET 53 1 A 365 650 365 180 Inv. 27 22 **OPS 39 1A 365 650 365 180 Inv. 28 22 ***paper *1 1 A 365 650 365 180 Inv. 29 23OPP 38 2 B 365/310 15/10 365/310 50/33 Inv. 30 23 PET 53 2 B 365/31015/10 365/310 50/33 Inv. 31 23 **OPS 39 2 B 365/310 15/10 365/310 50/33Inv. 32 23 ***paper *1 2 B 365/310 15/10 365/310 50/33 Inv. 33 24 OPP 382 B 365/310 15/10 365/310 50/33 Inv. 34 24 PET 53 2 B 365/310 15/10365/310 50/33 Inv. 35 24 **OPS 39 2 B 365/310 15/10 365/310 50/33 Inv.36 24 ***paper *1 2 B 365/310 15/10 365/310 50/33 Inv. 37 25 OPP 38 3 C380  40 380  80 Inv. 38 25 PET 53 3 C 380  40 380  80 Inv. 39 25 **OPS39 3 C 380  40 380  80 Inv. 40 25 ***paper *1 3 C 380  40 380  80 Inv.

[0267] <Evalution of Ink Jet Recording Images>

[0268] The resulting ink jet recording images under the three recordingcircumstances described above were evaluated in the same manner as inExample 1.

[0269] the results are shown in Table 2-8. TABLE 2-8 RecordingCircumstances 10° C., 20% RH 25° C., 50% RH 32° C., 80% RH SampleCharacter Color Character Color Character Color No. QualityContamination Quality Contamination Quality Contamination Remarks 21 B BC B D C Comp. 22 B B B D C D Comp. 23 B B B B D D Comp. 24 B B B C C DComp. 25 B B B B C B Inv. 26 B B B B B C Inv. 27 B B B B B B Inv. 28 A AB B B B Inv. 29 B A B A C A Inv. 30 B B B B B B Inv. 31 A A A A A A Inv.32 A A A A A A Inv. 33 B A B A B A Inv. 34 A A A A A B Inv. 35 B A B A BB Inv. 36 A B A B A B Inv. 37 B A B A B A Inv. 38 A B A B B B Inv. 39 AA A A A B Inv. 40 A A A A A A Inv.

[0270] As is apparent from Table 2-8 above, the image recording methodof the invention, which is carried out employing the inventive ink setscomprising the actinic ray curable composition of the invention, formsan image with high resolution with an excellent character quality, andexhibits no color contamination on various kinds of recording materials.

[0271] Effects of the Invention

[0272] The invention can provide an actinic ray curable composition andan actinic ray curable ink, which provide an image with high resolutionand excellent character quality, without causing color contaminationunder various recording circumstances, and an image recording method andan ink jet recording apparatus each employing the actinic ray curableink.

What is claimed is:
 1. An actinic ray curable composition containing aphoto acid generator, and an oxetane compound I represented by thefollowing formula 1,

wherein R₁, R₂, R₃, R₄, R₅, and R₆ independently represent a hydrogenatom, a fluorine atom, an alkyl group having from 1 to 6 carbon atoms, afluoroalkyl group having from 1 to 6 carbon atoms, an allyl group, anaryl group, a furyl group or a thienyl group, and wherein the longer C—Obond distance of the two C—O bond distances in formula 1 is from 0.1464to 0.1500 nm.
 2. The actinic ray curable composition of claim 1, whereinR₃, R₄, R₅ and R₆ in formula 1 atom are not simultaneously hydrogenatoms.
 3. The actinic ray curable composition of claim 1, wherein thecomposition further contains an oxetane compound II having one oxetanering which falls outside formula 1 or an oxetane compound III having twoor more oxetane rings.
 4. The actinic ray curable composition of claim1, wherein the composition further contains an oxirane compound havingan oxirane ring.
 5. The actinic ray curable composition of claim 1,wherein the composition has a viscosity at 25° C. of from 7 to 50 mPa.s.6. An actinic ray curable composition containing a photo acid generator,and an oxetane compound I′ represented by the following formula 1,

wherein R₁, R₂, R₃, R₄, R₅, and R₆ independently represent a hydrogenatom, a fluorine atom, an alkyl group having from 1 to 6 carbon atoms, afluoroalkyl group having from 1 to 6 carbon atoms, an allyl group, anaryl group, a furyl group or a thienyl group, and wherein in formula 1,the longer C—O bond distance of the two C—O bond distances is from0.1435 to 0.1461 nm, and the oxygen atom has a charge of from −0.330 to−0.281.
 7. The actinic ray curable composition of claim 6, wherein R₃,R₄, R₅ and R₆ in formula 1 atom are not simultaneously hydrogen atoms.8. The actinic ray curable composition of claim 6, wherein thecomposition further contains an oxetane compound II having one oxetanering which falls outside formula 1 or an oxetane compound III having twoor more oxetane rings.
 9. The actinic ray curable composition of claim6, wherein the composition further contains an oxirane compound havingan oxirane ring.
 10. The actinic ray curable composition of claim 6,wherein the composition has a viscosity at 25° C. of from 7 to 50 mPa.s.11. An actinic ray curable ink, containing pigment, a photo acidgenerator, and an oxetane compound I represented by the followingformula 1,

wherein R₁, R₂, R₃, R₄, R₅, and R₆ independently represent a hydrogenatom, a fluorine atom, an alkyl group having from 1 to 6 carbon atoms, afluoroalkyl group having from 1 to 6 carbon atoms, an allyl group, anaryl group, a furyl group or a thienyl group, and wherein the longer C—Obond distance of the two C—O bond distances in formula 1 is from 0.1464to 0.1500 nm.
 12. An actinic ray curable ink, containing pigment, aphoto acid generator, and an oxetane compound I′ represented by thefollowing formula 1,

wherein R₁, R₂, R₃, R₄, R₅, and R₆ independently represent a hydrogenatom, a fluorine atom, an alkyl group having from 1 to 6 carbon atoms, afluoroalkyl group having from 1 to 6 carbon atoms, an allyl group, anaryl group, a furyl group or a thienyl group, and wherein in formula 1,the longer C—O bond distance of the two C—O bond distances is from0.1435 to 0.1461 nm, and the oxygen atom has a charge of from −0.330 to−0.281.
 13. An image forming method comprising the steps of: ejectingdroplets of the actinic ray curable ink of claim 11 through a nozzle ofan ink-jet recording head onto a recording material to deposit the inkon the recording material; and irradiating the ink on the recordingmaterial employing an actinic ray, 0.001 to 2.0 seconds after theejected ink has been deposited on the recording material, whereby thecured ink layer is formed.
 14. The image forming method of claim 13,wherein the thickness of the cured ink layer is from 2 to 20 μm.
 15. Theimage forming method of claim 13, wherein the volume of the ink dropletsto be ejected is from 2 to 15 pl.
 16. The image forming method of claim13, wherein the ejecting of the actinic ray curable ink is carried outat 35 to 100° C.
 17. An image forming method comprising the steps of:ejecting droplets of the actinic ray curable ink of claim 12 through anozzle of an ink-jet recording head onto a recording material to depositthe ink on the recording material; and irradiating the ink on therecording material employing an actinic ray, 0.001 to 2.0 seconds afterthe ejected ink has been deposited on the recording material, wherebythe cured ink layer is formed.
 18. The image forming method of claim 17,wherein the thickness of the cured ink layer is form 2 to 20 μm.
 19. Theimage forming method of claim 17, wherein the ejecting of the actinicray curable ink is carried out at 35 to 100° C.